Four-fifths of the southern hemisphere and the more than three-fifths
of the northern hemisphere are under water. The Pacific, 70 million
square miles in area, is almost circular in shape and covers nearly
half the earth's surface. The Atlantic, at 36.3 million square
miles, forms a broad S with the two sides almost matching. The
Indian Ocean forms a large triangle with the Indian peninsula
protruding through the upper apex. The Arctic Ocean, with its
cover of floating ice, has an area of only 3.7 million squares
miles and is almost surrounded by land.

After looking around the web and reference books, I found that
the mass of the oceans is not always given in kilograms (kg).
Some of the values were given in grams and I had to convert them
to kilograms by multiplying by 1000. One of the sites didn't have
the mass of the oceans, but it did have their combined volume.
So I had to calculate the mass by using the formula D = m/V,
where D is density, m is mass, and V is volume. The density of
ocean water is approximately 1000 kilogram per cubic meter. One of my
sources had neither mass nor volume, but area in squares kilometers
and depth in meters. To obtain the mass, I multiplied area times
depth, times 10003 to get a result in kilograms.

After looking up all the sites and the information I gathered,
I have found that the mass of the world oceans is about 1.4 × 1021 kg.